Process of producing indanes from para-cymene



United States Patent "ice PRocEss 0F PRODUCENG INDANES FROM P YMENE Ernest H. Polak, Middletown, N. Y., assignor to lolaks Frutal Works, Inc.

No Drawing. Application October 9, 1953, Serial No. 385,261

11 Claims. (Cl. 260-668) This invention relates to the production of poly alkyl indanes from p-cymene. All percentages and parts herein are on a weight basis.

I have made the surprising and unexpected discovery that by reacting certain secondary and tertiary alcohols or alkenes containing from 4 to 12, preferably from 4 to 9, carbon atoms with p-cymene employing from 2 to 3 mols of p-cymene per mol of alcohol or alkene and in the presence of a liquid medium consisting of from 85% to 93% sulfuric acid and from 7% to 15% Water at a temperature of from 20 to 50 C. a poly alkyl indane or a mixture of poly alkyl indanes results. The alkenes should have the structural Formula I noted below, or

should have a structure such that it rearranges by shifting of the double bond to have this structural formula in which R1 and R2 are alkyl groups containing from 1 to 9, preferably 1 to 6, carbon atoms, R3 and R4 are either hydrogen or alkyl groups containing from 1 to 8, preferably l to 5, carbon atoms, R3 could be hydrogen and R; an alkyl group, or vice versa. The alcohols should be of the type that will split off water to form either an alkene having structural Formula I noted above, or an alkene which upon rearrangement has this structural formula. For example, in the case of methyl isobutyl carbinol (Formula II below) it dehydrates to 4-metl1yl-pentene-2 (Formula III below) which rearranges to 4-methyl-pentens-3 (Formula IV below) which can react with p-cymene to form an indane.

H H3 CH3 Formula II Formula III l Rearrangement CHr-CHz-CH=C-CHI Formula IV The presence of at least 7% water is essential; if less water is used the desired indanes are not produced in appreciable yields. The reaction desirably is carried out under atmospheric pressure conditions.

Thus, in accordance with my invention, p-cymene is reacted with tertiary amyl alcohol or tertiary amylene, employing from 2 to 3 mols of p-cymene per mol of alcohol or alkene and in the presence of from 85% to 93% sulfuric acid and from 7% to 15 water at a temperature of from 20 to 50 C., preferably 10 to 20 C., when using the alcohol, or at a temperature of 0 to 50 when employing tertiary amylene, producing a mixture of l,1,2,3,3,5 hexamethyl indane, 1,1,3,5 tetramethy1-3- 2,752,404 Patented June 26, 1956 ethyl indane and 1,1,3,3,5 pentamethyl indane. The substitution of corresponding secondary and tertiary alcohols or alkenes containing from 4 to 12 carbon atoms for the tertiary amyl alcohol or the tertiary amylene results in the production of corresponding indanes. Thus instead of tertiary amyl alcohol in the above reaction, one may use tertiary butanol, methyl isopropyl carbinol, methyl isobutyl carbinol, dimethyl isopropyl carbinol, methyl diethyl carbinol, dimethyl isobutyl carbinol, diisopropyl carbinol, diisobutyl carbinol, etc.

When reacting p-cymene with an alcohol from 1 to 5, preferably 1.5 to 4, parts by weight of sulfuric acid of the concentration noted are employed per part of p-cymene. When the reaction is carried out with an alkene, a lesser amount of sulfuric acid of the concentration noted is employed, because in this reaction none of the sulfuric acid is required to effect dehydration of the alcohol. Reacting an alkene with p-cymene from A; to 2, preferably A; to 1, parts of sulfuric acid of the concentration noted are used per part of p-cymene.

The indanes formed by the process of this invention are suitable for use as intermediates in producing pharmaceuticals, agricultural chemicals, dyes, odorants including musk odorants and those having a woody odor, etc. Thus, for example, by acetylating the indanes having from 14 to 16 carbon atoms, desirably at a temperature within the range of 0 to 60 (1., preferably 10 to 30 C., corresponding ketones are produced of pronounced musk odors. The acetylation may be effected by treating the individual indane or mixture thereof with acetyl chloride in the presence of aluminum chloride or other Friedel-Crafts catalyst.

Of the indanes above mentioned the methyl ketone derivative of 1,1,2,3,3,5 hexamethylindanehas the most pronounced musk odor. This methyl ketone derivative may be termed 1,1,2,3,3,5 hexamethyl indane-methyl ketone. The methyl ketone derivative of l,1,3,3,5 pentamethyl indane has a woody odor and can be used for the production of odoriferous materials, where such odor is desired. The mixture of indanes hereinabove identified may be acetylated to produce a mixture of methyl ketone derivatives having a strong musk odor. I

While the exact mechanism of the reaction is not fully understood it is believed that in the presence of the liquid medium containing from 7% to 15% water, the rest being sulfuric acid, hydrogen or hydrogen and a methyl group splits off from the alkylated cymene produced by the reaction of the p-cymene with the secondary or tertiary alcohol or alkene and ring closure also takes place with formation of the indane homologs. The reaction between p-cymene and tertiary amyl alcohol may be represented as follows:

tion. It will be understood that somewhat weaker acid,

say 96% acid, may be used in which case the number of parts of water added is adjusted to take into account the water present in the sulfuric acid. CH EXAMPLE 1 A mixture of 500 grams p-cymene and 125 grams tertiary amyl alcohol are added to a solution cooled to a temperature of C. in the flask, which solution con- 0-03; 10 tained 1286.4 grams of sulfuric acid and 113.6 grams of water. The mixture is added over a 2 hour period, care OH;-OGH, lil-OHOH;' being taken that the temperature of the mixture does not CH3 CH rise appreciably over 5 C. After completion of the H: addition of the p-cymene-amyl alcohol mixture, the reaction mixture is stirred for 5 hours allowing the temperature to rise to 10 C. The colorless oil layer is separated in a separatory funnel and washed with aqueous CHI dilute sodium hydroxide and water until neutral. The 5 neutral oil is then distilled under vacuum; a forerun of unreacted p-cymene and isopentane is first distilled over followed by the desired reaction product as a colorless liquid boiling at a temperature of 103 at 7 mm. of 0 OH; mcrcuryv Its density at 15 C. is 0906-0908. It consists of a mixture of about l,l,2,3,3,5 hexamethyl 25 indane, about 25% l,1,3,5 tetramethyl-B-ethyl indane and about 15% 1,1,3,3,5 pentamethyl indane, the rest being alkylated cymenes and other reaction products. Any in- Proof of the indane structure was confirmed by syndividual indanes may be isolated by fractional distillation, thesizing the indane compounds by conventional and recpreferably under vacuum. The properties of the indanes ognized reactions and comparing the properties of the are given in the following Table 1.

Table 1 7 Elements Anal is M 10 o w W Spgl'tyl'm, Name Formula at 2 mm. [01 1 131 Percent 0, Percent O, i g

HE PercentH PercentH m found calc.

- 6'. 275,4 1590 1,1,2,3,3,5hexamethyl-tndane OnHn s5 1. 5119 0.9119 66.57 as as 3 3 i8 9; $3 2 1275 262,25 880 276,1 1440 1,1,3,5tetramethyl-3-ethylindane..- 015m: 19% 1. 5049 0.8995 66.55 sass fig, fgfi Z22 2 1260 262,8 s70 275,8 1840 1;1,a,s,s pentamethylindane can as 1.5019 0.8911 62.34 62 1s I g 1430 262,4 990 resultant compounds with those produced by the process The mixture of poly alkyl indanes or the individual fof this invention. The Properties Were found to he idellfipoly alkyl indanes may be converted into the correspondcal. Also analysis of the chemical composition checks ing ketones by reaction with acetyl chloride in the preswith the indane formulas. Furthermore, the fact that ence of anhydrous aluminum chloride catalyst. Thus, hydrogen is split oif during the reaction is confirmed by 400 grams of pure nitrobenzene and 140 grams of anhyjthe fact that isopentane can be isolated from the lower drous aluminum chloride are agitated in the flask until boiling fractions of the reaction product in an amount l te di olution take place, The flask is cooled approximately equal to half the tertiary amyl alcohol with water to maintain it at a temperature below 30 C. or tertiary amylene reacted. The i'sopentane is derived 200 grams i dane product produced a de cribed above from the addition of hydrogen to the teltiery amylene and 85 grams of acetyl chloride are slowly added to the which is either already present or has been formed from it b t luminum hloride mixture by means of the tertiary y alcohol y the dehydrating action of the dropping funnel over a 3 hour period. During the the Sulfuric 1 acid catalysi- The formation of PP reaction the temperature is kept at about 20 C. by coolmately a half a mol of isopentane in the reaction product i ith water, wh h gas evolution ceases h is explained y the following equation: I action mixture .is. stirred for. an additional half hour. 1 mol p-cymene-l-l mol t-amyl alcohol (or 1 mol t- The thik 1iqu id mass e lll'odueed is Pe e h ice amylene) 0.5 mol p-cymene+0.5 mol isopentane+ Water whlle vlgorously stlrrmeand the stlrrmg 18 5 mol indane isomem tinued while adding hydrochloric acid until the complex d of the aluminum chloride is completely de- The following examples are g1ven for purposes of 11- compoun I lustration only; it will be understood the invention is f The resultant tieavy yellow on extracted not limited to these examples. In all of the examples Wlth P and Washed and sodmm acfitate the equipment used as a flask equipped with a ther solution until neutral. After dlstillmg ofi the solvent 640 mometer,' stirrer or agitator, a dropping funnel and a gas grams of mlxture of nm'obimzene wlth the ketofle are exhaust tuba obtained from which the mtrobenzene can easily be The number of parts of sulfuric acid given in the exseparated'by repeated distillation under vacuum. About amples is on a basis of sulfuric acid of concentra- 76 200 grams of pure idane methyl ketone product are ob- 5 tained. The properties of the indane methyl ketones'are given in Table 2 which follows:

of Colorless liquid which has a refractive index of N13 l.4979-1.4985. The resultant mixture of indanes may Table 2 Elementary Analysis M: O-M.P- 00 M P 24 oma .esemi- Name Formula 2mm. ing Point Percent 0, Percent C, carbag gggg Hg Percent H Percent H zone y found cale.

C. 1,1,2,3,3,5hexamethyl-indane-methylket0ne 01111240 131 1. 5322 58-59 }196198 162 164 yellow. 1,1,3,5 tetramethyl-3-ethyl indane methyl ketone. 01111240 117 1. 5285 31-32 3- 3-33 }168-170 Ill-142%. 1 1 3 3 t 83. 66 83. 43 178-180 red.

, pen amethyl lnclane methyl ketone CmH O 117 1.5228 5960 9 65 9 62 181 183 159 161% yellow.

EXAMPLE II A mixture of 710 grams of p-cymene and 200 grams of methyl-isobutyl-carbinol are added drop-wise while vigorously stirring over a 5 hour period, care being taken that the temperature of the reaction mixture does not rise above 15 C., to a liquid solution in the flask. The solution contains 1860 grams of sulfuric acid and 140 grams of water and had previously been cooled to 10 C. After completion of the addition the reaction mixture is stirred for 4 hours more at approximately 20 C. The colorless oil layer is separated in a separatory funnel and washed with dilute acqueous sodium hydroxide and water until neutral. The resultant liquid is distilled under vacuum. A forerun of unreacted p-cymene and pentane is distilled over first followed by a mixture of indanes at a constant temperature of 95 C. at 1.5 mm. of mercury in the form of a colorless liquid which has a refractive index N0 of 15035-15060. The resultant mixture of indanes may be acetylated in the same manner as described in Example I.

EXAMPLE HI A mixture of 800 grams p-cymene and 160 grams tertiary butyl alcohol are added, dropwise, while stirring over a 3 hour period, care being taken that the reaction temperature remains between lO and 0 C., to a liquid solution containing 1840 grams of sulfuric acid and 160 grams of water. After completion of the addition, the reaction mixture is stirred for 2 hours at 0 C. while cooling externally, followed by additional stirring for 2 hours without external cooling so that the temperature rises to to C. The oil layer is separated in a separatory funnel and washed with dilute aqueous sodium hydroxide and water until neutral. The resultant liquid is distilled under vacuum through an eflicient fractionating column. The forerun of unreacted p-cymene is recovered followed by 132 grams of indane fraction boiling at a constant temperature of 67.5 at 2.0 mm. of mercury in the form of a colorless liquid which has a refractive index of N0 of 15025-15028 and which consists principally of 1,1,3,3,5 pentamethyl indane. This product may be acetylated in the same manner as described in Example 1.

EXAMPLE IV A mixture of 875 grams of para-cymene and 360 grams of diisobutyl carbinol are added dropwise while stirring over a 3-hour period, care being taken that the temperature of the reaction mixture does not rise above 10 C., to a liquid solution in the flask containing 2110 grams of sulfuric acid and 182 grams of water. After completion of the addition, the mixture is stirred for 4 hours at 20 C. The oil layer is separated in a separatory funnel and washed with dilute aqueous sodium hydroxide and water until neutral. The resultant liquid is distilled under vacuum. A forerun of unreacted p-cymene is distilled over first followed by a mixture of indanes at a constant temperature of 118 C. at 2 mm. of mercury in the form be acetylated in the same manner as described in Example I.

It will be appreciated that mixtures of indanes including isomers result in carrying out the reaction of the above examples and that the expression indanes is used herein to include such mixtures.

By poly alkyl indane, as used herein, is meant an indane having only alkyl substituents. It will be understood that the compound or compounds herein referred to as indane or indanes are also called indan or indans', respectively.

It is to be understood that this invention is not restricted to the present disclosure otherwise than as defined by the appended claims.

What is claimed is:

1. A process of producing poly alkyl indanes from para-cymene, which comprises reacting para-cymene with a compound from the group consisting of secondary and tertiary saturated aliphatic alcohols and alkenes having from 4 to 12 carbon atoms, the alkenes in turn being from the group consisting of alkenes having the formula in which R1 and R2 are alkyl groups containing from 1 to 9 carbon atoms, R and R4 are from the group consisting of hydrogen and alkyl groups containing from 1 to 8 carbon atoms, and alkenes which rearrange to form an alkene having said formula and said alcohols are such that upon splitting oif of water they form an alkene from said group of alkenes, employing from 2 to 3 mols of para-cymene per mol of said compound at a temperature within the range of 20 to 50 C. in the presence of a solution containing from to 93% sulfuric acid and from 7% to 15% water. i

2. A process of producing poly alkyl indanes from para-cymene, which comprises reacting para-cymene with an alcohol from the group consisting of secondary and tertiary saturated aliphatic alcohols having from 4 to 12 carbon atoms which alcohols upon splitting off of water form an alkene from the group consisting of alkenes having the formula in which R1 and R2 are alkyl groups containing from 1 to 9 carbon atoms, R3 and R4 are from the group consisting of hydrogen and alkyl groups containing from 1 to 8 carbon atoms, and alkenes which rearrange to form an alkene having said formula, employing from 2 to 3 mols of para-cymene per mol of said alcohol at a temperature of from 20 to 50 C. in the presence of a solution containing from 85% to 93% sulfuric acid and from 7% to 15% Water.

3. The process as defined in claim 2, in which from 1 to 5 parts by weight of sulfuric acid are employed per part of para-cymene.

4. A process of producing poly alkyl indanes from "7 para-cymene, which comprises reacting para-cymene with an alkene :from the group consisting of alkenes having the formula in which R1 and R2 are alkyl groups containing from 1 to 9 carbon atoms, R3 and R4 are from the group consisting of hydrogen and alkyl groups containing from 1 to 8 carbon atoms, and alkenes which rearrange to form an alkene having said formula, employing from 2 to 3 mols ofpara-cymene per mol of alkene at a temperature of from to 50 C. in the presence of a solution containing from 85 to 93% sulfuric acid and from 7% to 15% water.

5. The process as defined in claim 4, in which from A; to 2 parts by weight of sulfuric acid are employed per part of para-cymene.

6. A process of producing poly alkyl indaues from para-cymene, which comprises reacting paracyrnene with an alcohol from the group consisting of tertiary butanol, methyl isopropyl carbinol, methyl isobutyl carbinol, dimethyl isopropyl carbinol, methyl diethyl carbinol, dimethyl isobutyl carbinol, diisopropyl carbinol and diisobutyl carbinol at a temperature of from l.0 to 20 C. in the presence of a solution containing from 85% to 93% sulfuric acid and from 7% to 15% water.

7. A process of producing a mixture of 1,1,2,3,3,5 hexamethyl indane, 1,1,3,5 tetramethyl-3-ethyl indane and 1,1,3,3,S pentamethyl indane, which comprises reacting paracymene with tertiary amylene employing from 2 to 3 mols of para-cymene per mol of tertiary amylene at a temperature of from 10 to 20 C. in the presence of a solution containing from 85 to 93% sulfuric acid and hem 7% to water.

8. A process of producing a mixture of 1,1,2,3,3,5 hexamethyl indane, 1,1,3,5 tetramethyl-3-ethyl indane and 1,1,3,3,5 pentamethyl indane, which comprises reacting para-cymene with tertiary amyl alcohol employing from 2 to 3 mols of para-cymene per mol of tertiary amyl alcohol at a temperature of from 10 to C. in the presence of about 85 to 93% sulfuric acid and 7% to 15 water.

9. A process of producing 1,1,3',3,5 pentamethyl indane, which comprises reacting para-cymene with tertiary butyl alcohol employing from 2 to 3 mols of para-cymene per mol of tertiary butyl alcohol at a temperature of from 10 to 20 C. in the presence of approximately 85% to 93% sulfuric acid and 7% to 15% water utilizing from 1.5 to 4 parts by weight of said acid per part of paracymene.

10. A process of producing poly alkyl indanes from para-cymeue, which comprises reacting para-cymene with an alcohol from the group consisting of secondary and tertiary saturated aliphatic alcohols containing 6 carbon atoms, which alcohol upon splitting ofi of water forms an alkene having the formula I I ia I l in which R1 and R2 are alkyl groups containing from 1 to 3 carbon atoms and R3 and R4 are from the group consisting of hydrogen and alkyl groups containing from 1 to 2 carbon atoms, employing from 2 to 3 mols of paracymene per mol of said alcohol at a temperature Within the range of from 20 to C. in the presence of a solution containing from to 93% sulfuric acid and from 7% to 15% water.

11. A process of producing poly alkyl indanes from para-cymene, which comprises reacting para-cymene with methyl-isobutyl-carbinol in the proportions of from 2 to 3 mols of para-cymene per mol of said methyl-isobutylcarbinol at a temperature of from 20 to 50 C. in the presence of a solution containing from 85% to 93% sulfuric acid and from 7% to 15% water.

References Cited in the file of this patent UNITED STATES PATENTS Barbier Mar. 13, 1934 Ipatietf et al Mar. 4, 1952 OTHER REFERENCES 

6. A PROCESS OF PRODUCING POLY ALKYL INDANES FROM PARA-CYMENE, WHICH COMPRISES REACTING PARA-CYMENE WITH AN ALCOHOL FROM THE GROUP CONSISTING OF TERTIARY BUTANOL, METHYL ISOPROPYL CARBINOL, METHYL ISOBUTYL CARBINOL, DIMETHYL ISOPROPYL CARBINOL, METHYL DIETHYLK CARBINOL, DIMETHYL ISOBUTYL CARBINOL, DIISOPROPYL CARBINOL AND DIISOBUTYL CARBINOL AT A TEMPERATURE OF FROM -10* TO 20* C. IN THE PRESENCE OF A SOLUTION CONTAINING FROM 85% TO 93% SULFURIC ACID AND FROM 7% TO 15% WATER. 